Technical Field
The present disclosure relates to an exhaust system for an internal combustion engine which is provided with an exhaust gas turbine supercharger (turbocharger) that drives a compressor of centrifugal type using exhaust gas energy, an exhaust gas purification catalyst that is arranged at the downstream side of a turbine of the turbocharger, and an exhaust gas sensor that is arranged between the turbine and the exhaust gas purification catalyst.
Description of the Related Art
In a construction in which a turbine of a turbocharger is arranged in an exhaust passage of an internal combustion engine, there may be formed a bypass passage bypassing the turbine. Then, in patent literature 1, there is disclosed a technology in which an air fuel ratio sensor is arranged in an exhaust passage at the downstream side of a turbine and a bypass passage. According to this technology, the air fuel ratio sensor is arranged in such a manner that, before an exhaust gas flowing out from the turbine into an exhaust passage (hereinafter, sometimes referred to as a “turbine exhaust gas”) is mixed with an exhaust gas flowing out from the bypass passage into the exhaust passage (hereinafter, sometimes referred to as a “bypass exhaust gas”), the air fuel ratio sensor is impinged by the turbine exhaust gas.
In addition, it has become common that an exhaust gas purification catalyst is arranged in an exhaust passage of an internal combustion engine at the downstream side of turbine of a turbocharger and a bypass passage. Then, in patent literature 2, there is disclosed a technology in which a wastegate valve (hereinafter, sometimes referred to as a “WGV”) is arranged in a bypass passage, wherein the WGV is opened at the time of cold start of an internal combustion engine. According to this technology, an exhaust gas purification catalyst arranged at the downstream side of the bypass passage is raised in temperature by using an exhaust gas of relatively high temperature having passed through the bypass passage.